As it is known, in wireless communication, a signal is often the object of dispersions, reflections, fading etc. . . . , causing the reception, within the receiver, of a multiplicity of signals shifted from one another, in many paths.
One treats these reflections, multiple dispersions of a signal by means of a rake receiver, which comprises a multiplicity of units (fingers) for the treatment of the various reflections, shifted one another, in order to allow, after treatment, the summation of all the elementary contributions of the reflections resulting from the multiple paths.
FIG. 1 illustrates the situation of a User Equipment 2 comprising a rake receiver 3 designed to process a number N of reflection paths distinct from the same signal emitted by a base station 1. For the sake of clarity, only three paths, respectively 11-13, are illustrated in FIG. 1 and represent three distinct contributions from the same signal arriving at shifted moments within the receiver, and with different amplitudes.
The communication protocols and in particular 3GPP require that a User equipment switches between idle and operating phases so as to avoid to miss a call signal coming from the base station. In this respect, it is important, in an obvious concern of economy of the lifespan of the battery, where the phase of operating lasts a minimal time and that, consequently, the process of assignment of various “fingers” of the rake receiver is carried out as soon as possible.
Generally, the fingers assignment of a rake receiver is carried out by means of a detection mechanism of a pilot (“Common Pilot Channel” (CPICH)) and of its possible reflections. For this purpose a measurement of the energy of the received signal is performed and a comparison with a threshold value, as that illustrated in FIG. 2, for detecting the various reflection paths. FIG. 2 shows that, after a first significant path of great amplitude corresponding to direct reception of the signal (Line of Sight), two reflection paths with less energy succeed. The mechanism of threshold detection is regulated so as to avoid the false detections (Constant False Alarm Rate (CFAR)), but it can omit one or more paths having less energy, as it is the case of the 2nd reflection in FIG. 2.
In order to maintain the efficiency of the process, one may consider to increase the processing time of the paths, which increase might clearly jeopardize the duration of the life of the battery.
For this reason, one wishes to be able to have a more effective process, being able to satisfy a reduced operation duration.